This invention relates to silicon carbide bodies and their production. It is particularly concerned with silicon carbide bodies (hereinafter referred to as "reaction-sintered silicon carbide bodies") produced by the reaction sintering of green bodies formed from a coherent mixture of silicon carbide and carbon, in the presence of molten silicon. This reaction sintering process is hereinafter referred to as "siliconising". The production of such bodies is described, for example, in U.S. Pat. Specification No. 3,495,939. They consist essentially of a substantially continuous matrix of silicon carbide particles bonded together and a substantially continuous free silicon phase.